The Flash ~ Season 1 - Episode 2 "Fastest Man Alive"

Iris is escorted by Barry to a university gathering, honouring Simon Stagg, a famous scientist. When six gunmen interrupt proceedings, Barry changes into the Flash only to pass out. While the scientists try to discover what's wrong with Barry, they realize that they're dealing with a metahuman who can replicate himself. Meanwhile, Iris becomes intrigued by the mysterious red streak fighting crime in Central City.